Portal de Periódicos da CAPES

Comparative tyrosine degradation in Vibrio cholerae strains. The strain ATCC 14035 as a prokaryotic melanogenic model of homogentisate-releasing cell

1998; Elsevier BV; Volume: 119; Issue: 3 Linguagem: Inglês

10.1016/s0305-0491(98)00028-5

1879-1107

Antonio Sánchez-Amat, Carolina Ruzafa, Francisco Solano,

Bacterial Genetics and Biotechnology

The relationship between l-tyrosine catabolism and melanin formation was studied in the Vibrio cholerae strains ATCC 14035 and CECT 557. It is shown that both strains degrade l-tyrosine by the same pathway as eukaryotic cells, giving homogentisate as intermediate. ATCC 14035, an O1 strain, which is not able to grow using l-tyrosine as sole carbon and energy source, but it forms pyomelanin from homogentisate. The second strain, which is non-O1, is able to grow using l-tyrosine as sole carbon and energy source, but it does not form any pigment. Both strains contain all the enzymes involved in the l-tyrosine catabolism. The three late enzymes of the pathway, homogentisate oxygenase, maleylacetoacetate isomerase and fumarylacetoacetate hydrolase, are induced by l-tyrosine, but the degree of induction is much lower in the ATCC 14035 strain. Thus, the distal part of the pathway becomes the rate-limiting steps in the l-tyrosine catabolism, explaining homogentisate accumulation and pyomelanogenesis in this strain. It is proposed that V. cholerae might be a useful prokaryotic model to show that alkaptonuria and other diseases related to l-tyrosine metabolism could occur in animals even when no particular enzyme involved in that pathway is lacking.